Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.math3.fraction; import java.io.Serializable; import org.apache.commons.math3.Field; import org.apache.commons.math3.FieldElement; /** * Representation of the fractional numbers without any overflow field. * <p> * This class is a singleton. * </p> * @see Fraction * @version $Id: BigFractionField.java 1416643 2012-12-03 19:37:14Z tn $ * @since 2.0 */ public class BigFractionField implements Field<BigFraction>, Serializable { /** Serializable version identifier */ private static final long serialVersionUID = -1699294557189741703L; /** Private constructor for the singleton. */ private BigFractionField() { } /** Get the unique instance. * @return the unique instance */ public static BigFractionField getInstance() { return LazyHolder.INSTANCE; } /** {@inheritDoc} */ public BigFraction getOne() { return BigFraction.ONE; } /** {@inheritDoc} */ public BigFraction getZero() { return BigFraction.ZERO; } /** {@inheritDoc} */ public Class<? extends FieldElement<BigFraction>> getRuntimeClass() { return BigFraction.class; } // CHECKSTYLE: stop HideUtilityClassConstructor /** Holder for the instance. * <p>We use here the Initialization On Demand Holder Idiom.</p> */ private static class LazyHolder { /** Cached field instance. */ private static final BigFractionField INSTANCE = new BigFractionField(); } // CHECKSTYLE: resume HideUtilityClassConstructor /** Handle deserialization of the singleton. * @return the singleton instance */ private Object readResolve() { // return the singleton instance return LazyHolder.INSTANCE; } }